Forum Discussion
Occasional ContributorSignalTap Invalid jtag (completely wiring dependent)
Dear support,
This issue has haunted me since 16.1 till 22.1std. SinglTap is not reliable.
And it is completely wiring dependent. I don't see hardware or setup issue, since reducing wiring will get a working SignalTap.
And sometime it fails even if there is 10 signals and 8K sample deep on a single clock domain. There is no timing error in build.
I've read all the threads relevant searched on this form, I don't think any of the recommendations help.
Please let me know, if there is anything I can do to reduce its occurrence.
Ouch.
Have you tried slowing the JTAG clock or making sure you have the JTAG timing constraints in your .sdc:
https://www.intel.com/content/www/us/en/docs/programmable/683081/22-2/jtag-signals.html
https://www.intel.com/content/www/us/en/support/programmable/articles/000084236.html
8 Replies
ShengN_alteraSuper Contributor
Below are some links for suggestions:
Also make sure to recompile and reprogram after making any changes.
Try to Scan Chain as well.
Thanks,
Best regards,
Sheng
sstrellOuch.
Have you tried slowing the JTAG clock or making sure you have the JTAG timing constraints in your .sdc:
https://www.intel.com/content/www/us/en/docs/programmable/683081/22-2/jtag-signals.html
https://www.intel.com/content/www/us/en/support/programmable/articles/000084236.html
- sstrell
When you say Signal Tap is not reliable, what exactly do you mean? Are you saying the captured samples don't match what you expect or is it not triggering on the trigger conditions you've specified? How full is your device? When you say that the design is meeting timing, is it meeting timing with Signal Tap both enabled and disabled?
RZhen11Hi sstrell,
Thanks for your attention.
I've never seen or captured samples mismatch, or no triggering.
My "reliable" means "Invalid JTAG Chain", the device is never more than 60% filled. Meeting timing means no timing error other than unconstrained warnings (those are expected with SignalTap insertions).
Basically, as long as I am able to see SignalTap after programming. I am happy. There is 10% percent chances I don't see it. Tried clean, rebuild. noprune attributes, all sorts. Most of the time, I had to use alternative method or nets to get moving.
Regards,
- sstrell
Ah, thought it was in the design. So you're probably having issues with programming the device itself as well.
There's a JTAG Chain Debugger tool in Quartus you could try. That might help identify a board issue, especially if there are other devices on your JTAG chain.
- RZhen11
Hi sstrell,
I've never had any issue programming, but when it's not "reliable" right after programming, I don't see SignalTap.
- sstrell
Weird. Is this a dev kit or a custom board? Can you try a different device? Does this happen with different designs? Could be a flaky device.
- RZhen11
Unfortunately this is a custom product, seeing the same issue through 20+ boards in the past 4 years since Quartus 16.1std.
